Neurobiological and neuroimaging biomarkers: A narrative review of precision medicine for diagnosing neurodegenerative disorders

Markers provide information about brain function, structure, and activity and are often used to study neurological and psychiatric conditions. This is crucial for diseases such as Parkinson’s disease, Alzheimer’s disease, autism, and Huntington’s disease. Neuromarkers describe distinct biological markers of these states, allowing for a new standard of earlier and more specific diagnosis than traditional symptom-based approaches. Herein, this review summarizes the current state of research on neurobiological and neuroimaging biomarkers in neurodegenerative diseases. Techniques, such as magnetic resonance imaging, positron emission tomography, and functional magnetic resonance imaging, play a crucial role in characterizing the structural, functional, and molecular imaging changes in the brain, offering new potential approaches for developing more precise treatment strategies tailored to individual patients. Neuroinflammation has became one of the most studied common pathological mechanisms involved in those diseases. Neurobiomarkers have been shown to reflect underlying immune phenomena. The presence of these neuroimaging markers, such as microglial activation or cytokine levels, can reveal a patient’s inflammatory status, allowing the differential diagnosis of disease states and tracking disease-specific pathophysiology. In Alzheimer’s and Parkinson’s diseases, for example, imaging biomarkers of tau and alpha-synuclein help differentiate subtypes and predict the potential utility of treatments, while in autism and Huntington’s disease, systems-level functional connectivity patterns serve as clues to underlying neural dysfunction. The clinical application of neuromarkers holds the potential to promote precision medicine, with the opportunity to develop treatments specifically for the neuromodulatory substrates of various diseases. Nevertheless, challenges remain in standardization and predictive validation of biomarkers between different race groups. Future studies should develop multimodal imaging, artificial intelligence-based analysis, and large-scale longitudinal studies to move the innovations toward practical diagnosis and therapeutic approaches, thereby improving the prognosis of patients with either neurodegenerative or neurodevelopmental disorders.